Alkali metal silicate powders and granules, especially sodium silicates, are important components of many detergent formulations. Many such formulations require the silicate to have particular physical characteristics such as a certain particle size and density. In general, small particles of silicate (smaller than 100 mesh) with various densities can be prepared by spray drying and the preparation of particles larger than 100 mesh with low densities (less than 25 lbs/ft.sup.3) is fairly routine since silicate particles are easily expanded by heating. This tendency toward expansion on heating renders it difficult to prepare relatively dense particles (bulk density more than 35 lbs/ft.sup.3) significantly larger than 100 mesh. Attempts have been made to prepare alkali metal silicate granules with such physical characteristics by compression or compaction techniques. These processes have not been completely successful. It has been necessary to use relatively high pressures to achieve compaction. These high pressures result in the development of relatively high temperatures to which the silicates are exposed during compaction. The silicates become adhesive at these temperatures and glassy bonding between the particles is accomplished but at the same time a build-up of glassy silicate on the compaction equipment is evident and interferes with the process. The glassy sheets produced by such methods are relatively thick and are difficult to grind with the consequent development of numerous fine particles (smaller than 100 mesh) that are unsuitable and must be recycled.
Other materials have also been subjected to compaction to increase the particle size. In one such process an inorganic salt is coated with a liquid hydrocarbon, subjected to a chemical etching step or a mechanical attrition step and then compressed. The resulting thin sheet is then granulated.